Aerial refueling by a tanker aircraft has become an accepted method of extending the duration of the flight of the receiver aircraft such as fighters, bombers and cargo aircraft. Two types of refueling systems have been used in the past. In United States Navy aircraft, the tanker trails a refueling drogue and the receiver aircraft maneuvers to insert a probe into the drogue to receive fuel from the tanker.
In the second refueling system used by United States Air Force aircraft, the tanker aircraft has a boom which extends from the rear of the aircraft and contacts a refueling receptacle in the receiver aircraft. One of the main advantages of this second system over the first is the ability of the tanker aircraft to transfer large quantities of fuel in a short period of time. The basis for the fast refueling capacity is a large diameter refueling pipe which is enclosed in an aerodynamically-shaped refueling boom. This second system has been the accepted means of refueling Air Force planes for over 20 years.
In the boom type system the pilots of both aircraft and a boom operator are in continuous radio communication. The receiver aircraft approaches the tanker from behind and below, and it is the boom operator's job to estimate the position of the receiver aircraft and determine when the receiver aircraft is within reach of the refueling boom. Due to the need of the boom operator to have a good view of the refueling operation so he can make the precise connection between the boom and the refueling receptacle of the receiver aircraft, the refueling operator has been located in the lower aft portion of the tanker aircraft where he has a direct out-the-window view of the boom and receiver aircraft. The boom operator lies prone in the rear of the tanker aircraft viewing the refueling boom and receiver aircraft through a window while flying the refueling boom with manual, hydraulically boosted controls. Refueling operations in this prone position are very fatiguing to the boom operator and his view of the refueling operation is limited. The remote location of the boom operator's station in the lower aft portion of the aircraft, away from the flight compartment, has meant that the boom operator has not been available for other activities in the flying of the tanker aircraft. The remote location of the station also means that the boom operator requires a separate life support system which is costly and necessitates modification of the rear frame of the aircraft.